Pre-Columbian purslane (Portulaca oleracea L) in the New World

LIKE so many cosmopolitan weeds, purslane (Portulaca oleracea L) has a history characterised by paradox and uncertainty. Most botanists have followed De Candolle¹ in assuming that it is native to the Old World and was introduced in the New World. There is, in fact, convincing historical evidence that the species was present in Europe before 1492 (ref. 2), and furthermore that it was introduced to North America in the seventeenth century³. On the other hand, the historical record also contains several anomalously early references to a wild purslane in the New World, and some botanists have argued that the species may have been present on both sides of the Atlantic before 1492 (ref. 4). Asa Gray even went so far as to suggest that the Vikings may have introduced it during their occupation of Greenland and Newfoundland⁵. We now present conclusive evidence that purslane was present in the New World in pre-Columbian times.